Inspection and recording device



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3 Claims.

This invention relates to contour inspection devices and is a division of my U. S. patent application filed August 11, 1947, Serial No. 768,039, now U. S. Patent No. 2,648,912. The invention herein relates more particularly to a recording device which, when used in conjunction with an inspection device of the type described in the aforementioned patent, provides a permanent record of the contour being inspected.

A device which has been used most effectively for the routine inspection of simple objects is the well known optical comparator. Briefly, it comprises a system of optica1 comparison, the image of the object to be inspected being compared against a standard drawing or outline of the object on a translucent screen. A source of light behind the object casts a shadow or image of the object which is then subjected to suitable magnification in an optical system and reflected upon the screen to be compared against the standard. While the results obtainable with optical comparators are commendable, it is difficult to foresee how, at the present state of the comparator art, such a device may be used without modification to inspect the complex objects as have been referred to hereinabove. Another limitation of the usual comparator, as well as many other inspection devices, is that a permanent record of the inspection results is not made. Such a record is often desirable.

Accordingly, this invention has as a purpose the provision of a device which may be used with an optical comparator to adapt it for the routine inspection as to form, dimensions, and angular relationships of objects defined by complex curved surfaces. A further purpose is to provide a deice for the inspection of complex curved surfaces which will permanently record the inspection results, and which will present a record from which the form, dimensions, and angular relationships may be determined. A still further purpose is to provide an inspection device of the nature described which may be operated by an unskilled person with a minimum of instruction. These and other purposes appearing hereinafter are accomplished by the present invention, an understanding of which may be had by reference to the accompanying drawings and the descriptive matter relating thereto. In the drawings,

Fig. 1 is a front view, partly in section, of a tracing unit embodying the principles of the present invention.

Fig. 2 is a side view, partly in section, of the tracing unit of Fig. 1.

Divided and this application June 8,

Fig. 3 is a representation of an optical comparator screen showing the manner of comparing the repeating styli images against master sections on the screen;

Fig. 4 is a side view, partly in section of a recording instrument in accordance with the invention;

Fig. 5 is a plan view of the recorder shown in Fig. 4;

Fig. 6 is a plan View of the recorder repeating arm gear housing unit, partly in section;

Fig. '7 is an end view, partly in section, of the gearing arrangement shown in Fig. 6;

Fig. 8 is a schematic diagram of an electrical system for connecting the tracing and recording units; and

Fig. 9 is a schematic diagram of an alternate electrical system for obtaining power amplification.

Briefly stated, the inspection device contemplated by the present invention comprises a pair of styli mounted in a tracing unit and movable in three rectangular coordinates, so that the styli may traverse any point of an object to be inspected, electrica1 means comprising a synchro or selsyn system to transmit intelligence resulting from the various motions of the styli, and a repeating or exhibiting unit where the motions are reproduced, permitting observation of the form, dimersions, and angular relationships of the object under inspection.

In one form of the invention the repeating unit is adapted to be used in conjunction with an optical comparator so that an object may be inspected, the image of which ordinarily cannot be projected onto a comparator screen because of interference with the light path by the warped and complex surfaces of the object.

Referring to Figs. 1 and 2 which show two views of the tracing unit I 00, the object to be inspected, 50!, is fixed in relation to the base 102 of the tracing unit by means of a suitable fixture not shown. The tracing of object IOI is accomplished by styli I03 and I04 which are designed to move in the vertical plane as they traverse any point of the object. Motion of the styli in the longitudina1 direction of object IOI, that is, in the direction as indicated by Fig. 2, is accomplished through frame I05 which is mounted on base E02 by suitable means such as balls I06 and I0! and gib plates I08 and I08a.

Frame I05 is shown as one casting extending from the base I02 to the top of the tracing unit. A stop mechanism I I2 attached to frame I05, and stop bar II3 are provided to limit the motion of frame I05, and thus facilitate the inspection of the object lI in several pl6d8t6lll1ll'l8d parallel planes, depending upon the number and spacing of the notches i M in bar I I3.

Motion of the styli in the transverse direction of object IOI, that is, in the direction as indicated by Fig. 1, and in a direction 90 degrees from the motion of the frame N35, is accomplished by carriage H which is mounted in frame I05 by means of balls H8 and ill, ways H0 and H0, and plate Mil. Way H3 is provided with stops I2I and 322 to limit the motion of the carriage at the extremities of its travel. The motion of carriage I W in turn is accomplished by the rotation of crank I23 which is geared through the armature shaft of synchronous electric generator I24 by means of a gear train to rack I21 mounted on the carriage H5. Generator I2 1 transmits the motion of the carriage to a repeating unit. The two styli I03 and I04 are provided with replaceable tips I28 and I29 of suitable shape and size, such as spherical with a radius of, say, about 1X34 inch, and are geared to two synchronous electric generators I35 and I3! which are mounted in fixed positions on carriage I I5. These generators transmit the motions of the styli in the vertical plane to the repeating unit. A. convenient manner of gearing the styli is shown in Fig. 5 of my patent referred to above and which forms no part of the present invention.

A repeating unit having styli corresponding to tracing styli I03 and I04 may be used to project the styli in enlarged form onto a screen as shown in Fig. 3. As described in my patent referred to above, the motions undergone by styli I03 and I04 are duplicated by repeating styli. The latter, being within the effective lens aperture of an optical comparator, permits the formation of their respective images by a light source on one side and the magnification and projection onto a comparator screen of these images by the com" parator optical system on the other side of the styli. The screen, having been provided with one or more large cross-sectional outlines of object IGI corresponding to the plane or planes in" spected, facilitates a comparison of the paths travelled by the repeating styli images against a standard. A comparator screen with several sections drawn thereon is illustrated by Fig. 3, showing the manner in which. the styli images may appear on the screen. The first plane of inspection, such as the one near the hub of object IOI described above, may correspond to section A on the screen. Since the images will move in accordance with the actual contours of the object under inspection, any deviations from the standard sections may be noted.

Upon completion of the inspection in one plane, such as that one referred to above, a second plane of inspection may e selected at any predetermined point of the object. The frame I05 of the tracing unit is then moved by lifting stop mechanism I I2 and manually sliding the unit on its base to the point where the styli reside in the desired plane. The stop mechanism is then released to engage the notch in stop bar H3 cor responding to the plane to be inspected, and fixing the frame I05 in that plane.

Instead of employing repeating styli, I now contemplate the use of a recording unit 400, so that a continuous record of the inspection results may be obtained. For this purpose the tracing unit of Figs. 1 and 2 is used. The differential generators I00 and I) as described and claimed in my patent referred to above are no longer necessary and need not be used, but the frame I05 is movable as before and may be locked in place by the stop and bar mechanism at any desired plane of inspection. Synchronous genorator I24, instead of being used a synchronous generator, is a synchronous motor and is operated from the recorder, although the mechanical means for moving carriage I I5, namely crank I23 and its associated mechanism, remains unchanged. The frame I05 is provided with a microswitch I39 which is operated by adjustable stop I40 on the carriage II5 to automatically limit the operation and motion of carriage H5 after a trace. Stylus synchronous generators I3l and HI function as described hereinabove.

The recording unit 400 is shown in Figs. nd 5. A roll of paper 40I is mounted in holders 2 353 by means of clamps 404 and 405 held in place by spring actuated members 405 and Q63. The paper is fed over a plate 408 and then over a driving roll 400 which is provided with teeth or sprockets at the ends thereof to engage with perforations on the sides of the paper, thus achieving a positive drive of the paper. Another roll, 4I0, presses against the driving roll, being under spring pressure, and maintains close contact between the paper and the driving roll. From the driving roll the paper passes over a curved plate 4| I, which guides it out to the end of the recording unit where a blade M2 is provided to facilitate tearing off the record after it has been made. The driving roll 409 is actuated by a constant speed elecwric motor M3 driving through a coupling and worm gear 4H! to ge 1 M5 on the driving roll shaft 416. The other side of the driving roll shaft is geared through gears 4I1 and4I0 to a pinion 4I0 of a synchronous electric generator 420. This generator is electrically connected to synchronous motor Ht of the tracing unit to effect motion of the tracing carriage H5 when the recorder is operated. The housing 42 I, shown in detail in Figs. 6 and 7, contains two synchronous electric motors 122 and 423 which are operated by impulses received from synchronous generators I30 and I3I of the tracing unit. Each synchronous motor is geared through a suitable gear train, such as pinion d2 3, gear 425, pinion 426 and gear 421 for one, and pinion 428, gear 429, pinion 430, and gear 53! for the other, to repeating arms 432 and 433 respectively. These arms swing in an arc, lightly loaded by means of springs 43 i and 435 to maintain unidirectional pressure of the teeth at all times, and further to provide a return for the arms. The actual recording on the paper is accomplished by points 4323 and 43'? which contain a writing compound, or, an electrio potential may be utilized between the points and plate 400 to register impressions on an electro-sensitive paper. The latter procedure presents little difficulty since housing MI is electrically insulated from the main recorder frame 438 by insulating bushings such as at 430 and an insulating plate 440. The circuit may be from a source of electrical potential through the housing 42I, arms 432 and 433, points 435 and 43?, plate 408, main frame 438, and back to the source.

Fig. 8 shows the electrical connections between the tracing and recording units. Referring to this and to Figs. 1, 2, 4 and 5, the mode of operation is as follows:

The object IOI to be inspected is placed in a fixed position with respect to the base I02 of the tracing unit. Using the stop mechanism H2 and stop bar II3, the frame is fixed in any desired plane of inspection. The stylus carriage H5 is then manually moved by crank I23 to a position where the styli are adjacent to the object II, in readiness to start the trace. The pushbutton cycle starting switch 20I is pushed, thereby causing starting relay 202 to close, and a holding contact 203 on the relay keeps the relay energized and closed, once the cycle has been started. At the same time, another contact 294 of the relay completes the circuit of recorder motor H3, putting the recorder paper in motion. This energizes synchronous generator 420 geared to the paper driving roll, and the impulses from this generator are transmitted to synchronous motor 525 of the tracing unit causing the tracing carriage II5 to traverse the object IElI. As soon as the carriage moves over the object, styli I03 and use energize synchronous generators I30 and IEI of the tracing unit. These impulses in turn are transmitted to synchronous motors 422 and 4-23 of the recorder, causing recorder arms A32 and 4433 to describe the contours of the object under inspection upon the recorder paper. The motions of the arms will be in proportion to the motions of the styli I03 and HM multiplied by a factor of amplification, this factor being a function of the physical proportions of the arms and their gear trains. For optimum results, the distance the recorder paper travels should be in proportion to the distance the carriage I I5 of the tracing unit travels, multiplied by the same factor of amplification as that of the arms. This factor, however, arises from the physical proportions of the gearing between the driving roll 409 and the synchronous generator 420. The combined effect of the motions of the arms and of the paper will cause the form of the object IIII to be drawn on the paper, and the outline so inscribed will be enlarged by the factor of amplification referred to above. The form will be modified, since a vertical motion of tracing stylus causes a repea-ting arm to swing an arc. Coordinate paper with arcs in one plane and straight lines properly spaced in the other may be 'used. After the tracing styli have passed over the object, the adjustable stop Hill on the tracing carriage contacts the microswitch I39 which opens the holding circuit of relay 2G2. This de-energizes the driving motor M3, stopping the recorder paper and the tracing carriage, and, since the synchronous motor system is de-energized, carriage i it may be reset to its starting position by means of crank I23. Any other section may then be traced using the above procedure. If electrical means are used to register the contours on the recorder paper, relay 202 may be provided with an additional contact to permit the application of an electrical potential between the recorder points and plate 408.

Whereas the recorder and tracing unit may be of light weight construction for a great many applications of the invention, it is conceivable that for some purposes, namely where relatively large objects are to be inspected, a much heavier tracing unit would be necessary. The question then arises whether or not the stylus carriage synchronous motor I24 would deliver sufficient torque to overcome the inertial and frictional resistance of such a system. Large synchronous motors and generators are available, or a means for providing power amplification, as is shown in Fig. 9, may be used. Here, the impulses from synchronous generator 329 of the recording unit are fed to the stator S of a synchronous control transformer Ill. The carriage II5 of the tracing unit is in this case operated by a D. C. motor I42 instead of a synchronous motor I24 which is replaced by the D. C. motor. Rotor R of the synchronous control transformer is geared to the D. C. motor so that the position of the D. C. motor armature may be compared, in an electrical sense, to the position of the armature of synchronous generator 420. A voltage is produced in rotor R of synchronous control transformer It! which is proportional to the difference in the angular positions of the two armatures, that is, the voltage is proportional to the error in the position of the armature of the D. C. motor. This error voltage is the output of the synchronous control transformer MI and is fed into a conventional vacuum tube control amplifier 26 5 which delivers impulses to the field coils of a D. 0. generator 206, operated by A. C. motor 201. The A. C. motor is driven from the same power source as that which is fed to synchronous generator @26. Output from the D. C. generator 2% drives D. C. motor I42, the field of which is supplied with a D. C. source of power by field supply rectifier 268. Switch 209 may correspond to contacts 293 and 204 of the starting relay shown in Fig. 8 to permit resetting of the carriage after each trace.

When the rotor of synchronous generator Me is moved from a state of rest through some small angle, a new direction of field is induced in the stator of synchronous control transformer I ll. The rotor winding of the control transformer, which has been in a state of zero induced voltage, will now develop a voltage due to the new direc tion of field of the stator. This voltage, increased by the amplifier 2% and fed to the field coils of D. C. generator 206, will cause the D. C. motor to rotate. Because the rotor of the control transformer is geared to the D. C. motor, it must rotate in step with that motor. Furthermore, this rotation is in a direction which will bring the rotor of the control transformer back to a position of zero induced voltage, and the D. C. motor will stop when it has moved through an angle equal to that through which the synchronous generator 42c has moved.

Power amplication of the impulses resulting from any other motions of the contour inspection device may be achieved in a similar manner, using a separate control transformer, amplifier, D. C. motor and motor-generator set for each motion.

The synchronous electric generators and motors of the present invention as referred to throughout the specification and in the appended claims are of the self-synchronous type commonly called selsyns.

It is perhaps apparent, but nevertheless significant, that the practice of the present invention, using either the optical comparator or the recorder embodiments, will permit the inspection and measurement of the pitch or angular relationships of an object in addition to its crosssectional contours. By observing the degree of slant from a norm for any particular cross-section, its pitch and the pitch of the object at that plane of inspection may readily be determined.

Although the embodiments of the invention specifically illustrated herein relate to a device using two styli, for some purposes where information regarding but one surface is desired, only one tracing stylus and one repeating stylus or recording arm would be necessary. On the other hand, more than two styli may be advantageously used to obtain simultaneous inspection at any deaceomsz sired number .of planes within practical limits by modifications which ,become apparent to those skilled in the art, they beingfamiliar with the present invention.

It isalso to be notedthat the invention may be practiced by using one or more styli which are fixed in two coordinates, but movablein accordance with the contours of the object under inspection, and moving the object in relation to the styli by means similar 'to that employed for moving the styli as set 'forth above. Then, the relative motion between the styli and the moving object may be resolved-alon two coordinates, and by synchronous electric means transmitted to exhibitingmeans to be observed as previously disclosed.

The invention is particularly advantageous where the large scale routine inspection of complex curved objects is desired. It provides a fast, efficient, and accurate inspection device which may be operated byan unskilled person, in contrast to common devices of the same character which are slow and require the extensive training of skilled personnel before such persons are qualified to operate them. However, once a per son familiar with the present invention has set up the inspection device and outlined a simple test procedure, any intelligent unskilled person can inspect even the most complex objects. Furthermore, by simply changin the electrical connections between the tracing and exhibiting means from one exhibiting means to another. which may be accomplished by an elementary switching mechanism, the device becomes adapted to produce a permanent record of the inspection results. Such a record is often desirable for research work on objects of the character described to compare their contours before and after operational tests are performed thereon.

Many changes and modifications may be made in the physical construction and in the electrical systems of the invention without departing from its spirit, and it is understood that the invention is not to be limited in its broadest aspect to such details or exemplifications as have been used to describe and illustrate it. The invention may be variously practiced and embodied within the scope ofthe claims hereinafter made.

I claim:

1. In a contour inspection device having tracing means including surface engaging means and synchronous eleotridgenerators associated therewith for generating electrical impulses in accordance with the contours of an object under inspection," exhibiting: means comprising a recorder frame, a roll of recording paper therein, a plate over which the paper is driven, means for driving the paper at a'constantspeed over the plate, a pair. of pivotally arrangedlarms adapted to swing man are on saidpaper and having a driven connection with synchronous electric motors associated with said recorder frame; means associated with eacharm for inscribing impressions on the paper;and means for supplying said synchronous electric motors with impulses from, said tracing'means in accordance with the contours of the object under inspection.

2. In a contour inspection device having tracing meansincluding surface engaging means, a synchronouselectric motor for causing the surface engaging means to trace the contours of an object under inspection, and synchronous electric generators associated with said surface engaging means for generating electrical impulses in accordance with'the contours of said object, exhibiting means comprising a recorder having a recording medium associated therewith, a constant speed electric motor for driving the recording medium, a synchronous electricgenerator having a driven connection with said constant speed motor to drive saidsynchronous electric motor in the tracing means. in proportion to the speed of said recording medium, means for inscribing the contours of said object upon the recording medium, synchronous electric motors having a driving connection with. saidinscribingmeans and operatively controlled by'impulses received from said synchronous-electric generators in the tracing means, whereby the contours of the object under inspection are reproduced;

3. A contour inspection device comprising a base, a frame cooperable therewith in a defined path and capable of assuming a fixed position along said path, a movablecarriage thereon cooperating therewith in a second path degrees of the aforesaid path; a surface engaging member References Cited in the file of this patent UNITED STATES PATENTS Name Date Lobosco Jan. 17, 1950 Number 

